This product is a replacement lower connector for the Kangertech Protank 2 3.5ml BCC.  This product is the piece that is directly below the glass that includes the kanger logo and branding and connects to the top cap by screwing onto the center tube inside the tank to hold the glass in place.   

It is simply a replacement part to be used if your protank base has been lost or damaged.  It cannot be used without the remainder of the protank pieces found below:

• KangerTech Protank 2 Replacement Base
• KangerTech Protank 2 Replacement Pyrex Tube
• KangerTech Protank 2 Replacement Top Cap w/ Drip Tip